Functional groups in biomolecules

The carbonyl functionality is one of the most abundant functional groups in biomolecules and pharmaceuticals, including many a- and /3-carbonyl derivatives of ketones and aldehydes and their enol tautomers, which upon deprotonation can form entropy-favored 5-membered (37) and 6-membered (38) chelates with metal ions. In this section, the role of metal ions in the action of some enol-containing biochemicals and pharmaceuticals and the structures of their metal complexes are discussed. 

FIGURE 1-15 Some common functional groups of biomolecules. In this figure and throughout the book, we use R to represent "any substituent." It may be as simple as a hydrogen atom, but typically it is a carbon-containing moiety. When two or more substituents are shown in a molecule, we designate them R1, R2, and so forth. 

FIGURE 1-16 Several common functional groups in a single biomolecule. Acetyl-coenzyme A (often abbreviated as acetyl-CoA) is a carrier of acetyl groups in some enzymatic reactions. 

The main experimental parameter in IR is the frequencies (e.g. v for stretching, 5 for in-plane bending and y for out-plane bending) of the absorption bands characterizing functional groups, in particular Vc=o and Vn-h for biomolecules. The vibrational frequency Vyib of a bond can be approximately described by the formula... 

---